JPH0841934A - Hydraulic circuit for working vehicle - Google Patents

Abstract

PURPOSE:To drive each actuator at the desired speed by leading the discharge oil of both hydraulic pumps to the first and second hydraulic actuators at the time of operating a first and a second operating member simultaneously. CONSTITUTION:When an arm control lever 12 and a reserve control pedal 1 are operated in the directions of arrow marks, a reserve control valve 4 and an arm control valve 10 are switched by the secondary pressure of a pilot valve 3, so that the discharge oil of two main pumps 5, 11 are merged and led to a reserve cylinder 6. Out of discharge oil from the main pump 11, the quantity of pressure oil led to the reserve cylinder 6 from a line 27 by the throttle 61 of a line 32 is more than the quantity of pressure oil led to an arm cylinder 15 from the line 32, so that the opening/closing speed of a breaker does not become slow even at the combined action time of the rise of an arm and the opening/closing of the breaker. This relation is held in the same way also at the combined action time of the descent of the arm and the opening/ closing of the breaker by operating the reserve control pedal 1 in the direction of the arrow mark while operating the arm control lever 12 in the reverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work hydraulic circuit provided in a work vehicle such as a hydraulic excavator, and more particularly to a work hydraulic circuit capable of performing a combined operation of two work attachments.

[0002]

2. Description of the Related Art As a work vehicle provided with this kind of work hydraulic circuit, for example, one shown in FIG. 4 is known. This work vehicle includes a hydraulic excavator main body 51, a boom 52 connected to the main body 51, an arm 53 connected to the tip of the boom 52, and a crusher 54 as a preliminary attachment connected to the tip of the arm 53. Have.
Reference numeral 55 is a boom cylinder for vertically moving the boom, and 15 is an arm cylinder for vertically driving the arm 53.

FIGS. 5 to 7 show a conventional working hydraulic circuit provided in the hydraulic excavator, which is for driving and controlling the arm cylinder 15 and the spare cylinder 6 for opening and closing the crusher. is there. In the state of FIG. 5, when the auxiliary control pedal 1 is stepped on in the direction of the arrow to drive the crusher 54 independently, the discharge pressure from the pilot hydraulic pump 2 is reduced by the pilot valve 3, and the reduced secondary pressure is generated. It acts on the pilot port 4 a of the preliminary control valve 4 through the pilot line 21. As a result, the preliminary control valve 4 is switched as shown in FIG. 6, and the oil discharged from the main pump 5 passes through the pipe line 22, the preliminary control valve 4 and the pipe line 23 to the bottom chamber of the auxiliary cylinder (crusher driving cylinder) 6. Be led to.

At this time, the secondary pressure of the pilot valve 3 is the pilot pressure of the arm control valve 10 via the pilot pipe line 24, the shuttle valve 7, the priority valve 8, the pipe line 25, the shuttle valve 9 and the pipe line 26. It also acts on the port 10a, which causes the arm control valve 10 to switch as shown in FIG. As a result, the oil discharged from the main pump 11 is guided to the bottom chamber of the spare cylinder 6 via the arm control valve 10, the pipe 27, the preliminary control valve 4 and the pipe 23. That is, when the preliminary control pedal 1 is independently operated, the oil discharged from the two main pumps 5 and 11 merges and is guided to the preliminary cylinder 6, whereby the crusher 54 is driven via the preliminary cylinder 6.

On the other hand, in order to drive the crusher 54 at the same time while raising (dumping) the arm 53, that is, the arm 53
When the arm control lever 12 and the preliminary control pedal 1 are operated in the directions of the arrows to perform the combined operation of the crusher 54 and the crusher 54, the state shown in FIG. That is, similarly to the above, the preliminary control valve 4 is switched, and the oil discharged from the main pump 5 is guided to the bottom chamber of the preliminary cylinder 6 via the pipe line 22, the preliminary control valve 4, and the pipe line 23.

At this time, the secondary pressure of the pilot valve 3 is also guided to the priority valve 8 via the pipe line 24 and the shuttle valve 7, and the priority valve 8 of the pilot valve 13 accompanying the operation of the arm control lever 12. The position is switched to the position shown in FIG. 7 by the secondary pressure (pressure in the conduit 30), so that the selected pressure of the shuttle valve 7 does not act on the shuttle valve 9, that is, the pilot port 10a of the arm control valve 10. The secondary pressure of the pilot valve 13 is
Pilot port 10b of arm control valve 10 via 9
, Which causes the arm control valve 10 to switch to the position of FIG. Therefore, the discharge oil of the main pump 11 is blocked by the control valve 10 and does not flow to the pipe line 27, that is, the preliminary control valve 4, and as a result, the hydraulic pump 5 flows to the preliminary cylinder 6.
Only the discharge oil of can be guided.

On the other hand, the secondary pressure of the pilot valve 13 also acts on the pilot port 14a of the arm control valve 14 via the conduits 28 and 31, whereby the arm control valve 14 is switched to the position shown in FIG. As a result, the oil discharged from the main pump 5 is guided to the bottom chamber of the arm cylinder 15 via the arm control valve 14, and the main pump 11
Is also introduced into the bottom chamber of the arm cylinder 15 via the pipe 32 and the arm control valve 14. That is, the oil discharged from the two main pumps 5 and 11 joins and is guided to the arm cylinder 15, whereby the arm 53 is raised via the arm cylinder 15.

When the arm control lever 12 is operated in the direction opposite to that described above and the preliminary control pedal 1 is operated in the direction of the arrow, the secondary pressure of the pilot valve 13 is guided to the pilot port 14b of the arm control valve 14. Then, the control valve 14 is switched and the main pumps 5, 11
The discharge oils of the above join and are guided to the rod chamber of the arm cylinder 15. This causes the arm 53 to descend. At this time, the secondary pressure of the pilot valve 13 is also guided to the pilot port 10a of the arm control valve 10 via the shuttle valve 9 and the conduit 26, so that the arm control valve 1
0 is switched to the position shown in FIG. 6, and the oil discharged from the main pump 11 is also guided to the pipe line 27. Therefore, the oil discharged from the two main pumps 5 and 11 is guided to the bottom chamber of the spare cylinder 6.

[0009]

As described above, in the conventional circuit (arm priority circuit), when the crusher 54 is independently operated, and when the arm lowering operation and the crusher opening / closing operation are combined. The oil discharged from the two main pumps 5 and 11 is guided to the spare cylinder 6, but when the combined operation of the arm raising operation and the crusher opening / closing operation is performed, the spare cylinder 6 has one main pump 5 Only the discharge oil of can be guided. Therefore, there is a problem that the opening / closing speed of the crusher 54 becomes slow when opening / closing the crusher 54 while raising the arm 53.

It is an object of the present invention to provide a work vehicle improved so that when a combined operation for simultaneously driving two hydraulic actuators is performed, both actuators can be driven at a desired speed regardless of the driving direction of the actuators. To provide a hydraulic circuit.

[0011]

When the invention of claim 1 is described in association with FIG. 1 showing an embodiment, the invention of claim 1 is directed to first and second hydraulic pumps 11 and 5, and first and second hydraulic pumps. The actuators 15, 6 and the first and second hydraulic pumps 11,
Control valve means 14, 10, 4 for controlling the pressure oil guided from 5 to the first and second actuators 15, 6, and control valve means 14 according to the operation of the first and second operation members 12, 1. ，
And a switching control means 100 for switching control of 10 and 4,
The first operation of the first operating member 12 drives the first hydraulic actuator 15 in the first direction, and the second operation of the first operating member 12 causes the first hydraulic actuator 15 to move in the second direction. It is applied to a hydraulic circuit of a work vehicle which is driven to drive the second hydraulic actuator 6 according to the operation of the second operating member 1. The above-mentioned problems are solved by configuring the switching control means 100 as follows. That is, when the first and second operation members 12 and 1 are simultaneously operated, the switching control means 100 determines whether the operation of the first operation member 12 is the first operation or the second operation, The control valve means 14, 10, 4 are switched and controlled so that the discharge oils of the first and second hydraulic pumps 11, 5 are guided to both the first and second hydraulic actuators 15, 6. The invention of claim 2 provides the first and second hydraulic pumps 1
1, 5 and the first and second hydraulic actuators 15,
6, a communication position for guiding both the discharge oils of the first and second hydraulic pumps 11 and 5 to the first hydraulic actuator 15, and the first and second hydraulic pumps 11 and 5 and the first hydraulic actuator 15. First switchable position to shut off
Control valve 14 and the discharge oil of the first hydraulic pump 11 to the second
Communication position leading to the hydraulic actuator 6 side of the
Of the second hydraulic pump 11 that can be switched to a shut-off position that blocks the discharge oil of the hydraulic pump 11 from being guided to the second hydraulic actuator 6 side.
Control valve 10 and a communication position for guiding both the discharge oil of the second hydraulic pump 5 and the pressure oil from the second control valve 10 to the second hydraulic actuator 6, and the second hydraulic pump 5 and the second hydraulic pump 5. A third control valve 4 that can be switched to a shut-off position that shuts off the control valve 10 and the second hydraulic actuator 6, and the first to third depending on the operation of the first and second operation members 12 and 1.
Switching control means 1 for switching control of the control valves 14, 10, 4 of
00, the first hydraulic actuator 15 is driven in the first direction by the first operation of the first operating member 12, and the first hydraulic actuator 15 is operated by the second operation of the first operating member 12. Is driven in the second direction, and the second hydraulic actuator 6 is driven according to the operation of the second operating member 1.
When the first and second operation members 12 and 1 are operated simultaneously, the operation of the first operation member 12 is the first operation and the second operation.
In any of the above operations, the first to third control valves 14,
The switching control means 100 is configured to switch both 10 and 4 to the communication position, thereby solving the above problems.
According to the invention of claim 3, the switching control means comprises a first switching means for switching the first control valve to the communicating position by the pressure generated by the first and second operations of the first operating member, and a second switching means. The second control valve is configured to be switched to the communication position by the pressure generated by the operation of the operation member. A fourth aspect of the invention is to provide a flow rate adjusting means for adjusting the flow rate so that the flow rate of the discharge oil of the first hydraulic pump that is guided to the first control valve is greater than the flow rate that is guided to the second control valve. It is further equipped. The invention of claim 5 is
The first and second hydraulic actuators drive the first and second work attachments, respectively. According to a sixth aspect of the present invention, the first hydraulic actuator is a hydraulic cylinder for raising and lowering the arm, and the second hydraulic actuator is the second hydraulic actuator.
The actuator is a hydraulic cylinder for driving a spare attachment.

[0012]

[Action]

(1) Invention of Claim 1 When the first and second operation members 12, 1 are simultaneously operated,
Whether the operation of the first operation member 12 is the first operation or the second operation, the first and second hydraulic actuators 1
The discharge oils of the first and second hydraulic pumps 11 and 5 are guided to both 5 and 6. As a result, both the first and second actuators 15 and 6 are driven at a desired speed. (2) Invention of Claim 2 When the first and second operation members 12, 1 are simultaneously operated,
Regardless of whether the operation of the first operation member 12 is the first operation or the second operation, the first to third control valves 14, 10, 4
Are switched to the communication position. As a result, the discharge oils of the first and second hydraulic pumps 11 and 5 are both guided to the first hydraulic actuator 15 via the first control valve 14, and the pressure oil that has passed through the second control valve 10 is also supplied. (First
Of the hydraulic pump 11) and the second hydraulic pump 5
Is discharged to the second hydraulic actuator 6 through the third control valve 4. As a result, similarly to the above, both the first and second actuators 15 and 6 are driven at a desired speed.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to the hydraulic circuit of the work vehicle shown in FIG. 4 will be described with reference to FIGS. In addition,
The same parts as those in FIGS. 5 to 7 are designated by the same reference numerals, and differences will be mainly described. In the conventional circuit (arm priority circuit) shown in FIGS. 5 to 7, the pilot conduit 28 is provided in the arm control valve 10.
The pilot port 10b, the pilot port 14a of the arm control valve 14, and the pilot port 8a of the priority valve 8 were connected to each other, but in the circuit of this embodiment (preliminary priority circuit), the pilot conduit 28 is connected to the arm control valve. The pilot port 14a of 14 and the A port of the priority valve 8 are connected.

Further, in the conventional circuit, the output side of the shuttle valve 7 is connected to the A port of the priority valve 8 and the B port of the priority valve 8 is connected to the input side of the shuttle valve 9, respectively, but in the circuit of this embodiment, The output side of shuttle valve 7 is connected to the input side of shuttle valve 9 via line 33, and is also connected to pilot port 8a of priority valve 8 via line 34. Further, the B port of the priority valve 8 is connected to the pilot port 10b of the control valve 10 via the pipe 35. Other configurations are the same as those of the conventional circuit.

The operation of the hydraulic circuit configured as above will be described. (1) Crusher independent operation When the auxiliary control pedal 1 is operated in the direction of the arrow in order to open / close the crusher 54 alone in the state of FIG. 1, the secondary pressure of the pilot valve 3 causes the pilot conduit 21 The pilot control valve 4 acts on the pilot port 4a of the backup control valve 4 through the switch, and the backup control valve 4 is switched as shown in FIG. As a result, the oil discharged from the main pump 5 is guided to the bottom chamber of the spare cylinder 6 via the conduit 22, the auxiliary control valve 4, and the conduit 23.

At this time, the secondary pressure of the pilot valve 3 also acts on the pilot port 10a of the arm control valve 10 via the pipe line 24, the shuttle valve 7, the pipe line 33 and the shuttle valve 9. On the other hand, the pilot port 10b of the control valve 10 communicates with the tank through the priority valve 8 which is switched to the position shown in FIG. 2 by the pressure in the pipe 34, and therefore the arm control valve 10 is brought to the position shown in FIG. Switch. As a result, the oil discharged from the main pump 11 is guided to the bottom chamber of the spare cylinder 6 via the arm control valve 10, the pipe line 27, the preliminary control valve 4 and the pipe line 23. That is, similarly to the conventional example, the discharge oils of the two main pumps 5 and 11 merge and are guided to the spare cylinder 6,
As a result, the crusher 54 is driven via the spare cylinder 6.

(2) Combined operation of raising the arm and opening / closing the crusher When the arm control lever 12 and the spare control pedal 1 are operated in the directions of the arrows in FIG. The state shown in FIG. 3 is obtained. In other words, the secondary pressure of the pilot valve 3 switches the preliminary control valve 4 and the arm control valve 10 to the same positions as those in FIG. 2, and in this case as well, the discharge oils of the two main pumps 5 and 11 merge and the preliminary cylinder 6 Be led to. Moreover, since the throttle 61 is provided in the pipe 32, the pipe 27 of the oil discharged from the main pump 11 is discharged.
The amount of the pressure oil guided to the spare cylinder 6 via the above is larger than the amount of the pressure oil guided to the arm cylinder 15 via the pipe line 32 as described later. Therefore, the opening / closing speed of the crusher 54 does not slow down even during the combined operation of raising the arm and opening / closing the crusher.

On the other hand, the secondary pressure of the pilot valve 13 generated by the operation of the arm control lever 12 is
It acts on the pilot port 14a of the arm control valve 14 via the line 28, which switches the arm control valve 14 to the position of FIG. As a result, the oil discharged from the main pump 5 is guided to the bottom chamber of the arm cylinder 15 via the arm control valve 14, and the oil discharged from the main pump 11 is also guided to the arm cylinder 15 via the conduit 32 and the arm control valve 14. Get burned. That is, the two main pumps 5, 1
The discharged oil of No. 1 joins and is guided to the arm cylinder 15, and the arm 53 rises in synchronization with the opening and closing of the crusher 54.

(3) Combined operation of arm lowering and crusher opening / closing When the auxiliary control pedal 1 is operated in the arrow direction while operating the arm control lever 12 in the direction opposite to the above in the state of FIG. 1, the pilot valve The secondary pressure of 13 is guided to the pilot port 14b of the arm control valve 14, so that the arm control valve 14 moves to the pilot port 14b.
Switch to the side position. Further, the control valves 4 and 10 are switched to the same positions as in FIG. Therefore, the oil discharged from the two main pumps 5 and 11 joins each other and is guided to the bottom chamber of the spare cylinder 6 and the rod chamber of the arm cylinder 15, whereby the crusher 54 is driven to open and close.
The arm 53 descends. Also in this case, the diaphragm 61 of the pipe 32
Due to the above action, the amount of pressure oil guided to the spare cylinder 6 via the pipe 27 is larger than the amount of pressure oil guided to the arm cylinder 15 via the pipe 32. Therefore, the opening / closing speed of the crusher 54 does not slow down even during the combined operation of lowering the arm and opening / closing the crusher.

In each of the above cases, the case where the auxiliary control lever 1 is operated in the direction of the arrow is shown. The same operation as described above is performed except that the opening / closing direction of the machine 54 is different.

When the preliminary control lever 1 is not operated, the priority valve 8 is switched to the state shown in FIG. 1 because the pressure in the conduit 33 (34) is low.
Therefore, at this time, when the arm control lever 12 is independently operated in the arrow direction, that is, in the arm rising direction, the secondary pressure of the pilot valve 13 passes through the pipe line 28 and the priority valve 8 and the pilot port 10b of the arm control valve 10 operates. The control valve 10 is switched to the position shown in FIG. Therefore, the oil discharged from the main pump 11 is not guided to the pipe line 27, but almost the entire amount is joined with the oil discharged from the main pump 5 and guided to the arm control valve 14, that is, the arm cylinder 15.

When the arm control lever 12 is independently operated in the opposite direction (arm descending direction), the secondary pressure in the pilot case 13 is the shuttle valve 9.
Since it acts on the pilot port 10a of the arm control valve 10 via the pipe line 26 and the pipe line 26, the control valve 10 is switched to the position shown in FIG.
Guided by both sides. Therefore, when the arm is lowered, the amount of pressure oil guided to the arm cylinder 15 is smaller than when the arm is raised, but there is no problem because the weight of the arm acts.

As described above, in this embodiment, the preliminary priority circuit can be constructed by slightly changing the connection of the pilot circuit without changing the main circuit of the conventional arm priority circuit. If desired, it can be immediately returned to the arm priority circuit. Further, in the preliminary priority circuit, the driving speed of the arm 53 is slightly slower in the combined operation as compared with the arm priority circuit, but an excellent effect that the opening / closing speed of the preliminary attachment (here, the crusher 54) is significantly increased. Can play.

In the configuration of the above embodiment, the main pumps 11 and 5 serve as the first and second hydraulic pumps, the arm cylinder 15 and the spare cylinder 6 serve as the first and second hydraulic actuators, and the control valves 14 and 10. , 4 are control valve means (first to third control valves), and pilot valves 3, 1
3, shuttle valve 7, 9, priority valve 8,
The pipe lines 21, 24, 26, 28, 33, 34, 35 serve as the switching control means 100, the arm control valve 12 and the preliminary control pedal 1 serve as the first and second operating members, and the arm 53 and the crusher 54 serve as the first. The first and second work attachments and the throttle 61 constitute flow rate adjusting means.

The first and second work attachments are not limited to the arm 53 and the crusher 54, but may be other actuators. Further, although the hydraulic circuit of the working vehicle based on the main body of the hydraulic excavator has been described, the present invention can be applied to the hydraulic circuits of other working vehicles.

[0027]

According to the first and second aspects of the present invention, when the first and second operating members are simultaneously operated, the operation of the first operating member is either the first operation or the second operation. However, since the discharge oils of the first and second hydraulic pumps are both guided to both the first and second hydraulic actuators,
When the combined operation of two hydraulic actuators is performed, both actuators can be driven at a desired speed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a hydraulic circuit of a work vehicle according to an embodiment of the present invention, showing a state in which no operation is performed.

FIG. 2 is a circuit diagram showing a state in which the crusher is independently driven.

FIG. 3 is a circuit diagram showing a state where a combined drive operation of an arm and a crusher is performed.

FIG. 4 is a diagram showing an example of a work vehicle in which a hydraulic circuit according to the present invention is mounted.

FIG. 5 is a circuit diagram showing a conventional example of a hydraulic circuit of a work vehicle, showing a state in which no operation is performed.

FIG. 6 is a conventional circuit diagram showing a state in which the crusher is independently driven.

FIG. 7 is a conventional circuit diagram showing a state where a combined drive operation of an arm and a crusher is performed.

[Explanation of symbols]

 1 Spare control pedal 3,13 Pilot valve 4 Spare control valve 5,11 Main pump 6 Spare cylinder 7,9 Shuttle valve 8 Priority valve 12 Arm control lever 15 Arm cylinder 10,14 Arm control valve 21 to 35 Pipe line 53 Arm 54 Crusher 61 Throttle 100 Switching control means

Claims (6)

[Claims] 1. Controlling first and second hydraulic pumps, first and second hydraulic actuators, and pressure oil guided from the first and second hydraulic pumps to the first and second actuators. Control valve means for controlling the control valve means according to the operation of the first and second operation members, and the first operation of the first operation member for the first operation. A hydraulic actuator is driven in a first direction, the first hydraulic actuator is driven in a second direction by a second operation of the first operating member, and the first hydraulic member is driven in a second direction by the operation of the second operating member. In a hydraulic circuit of a work vehicle configured to drive a second hydraulic actuator, the switching control means controls the operation of the first operating member when the first and second operating members are simultaneously operated. Operation 1 and operation 2 Even if there is a deviation, the work vehicle is characterized in that the control valve means is switched and controlled so that the discharge oils of the first and second hydraulic pumps are guided to both of the first and second hydraulic actuators. Hydraulic circuit. 2. A first and a second hydraulic pump, a first and a second hydraulic actuator, and a communication position for guiding the discharge oil of the first and the second hydraulic pump together to the first hydraulic actuator, And a first control valve that can be switched to a shut-off position that shuts off the first and second hydraulic pumps and the first hydraulic actuator, and discharge oil of the first hydraulic pump to the second hydraulic actuator. And a second control valve that can be switched to a communication position that guides the discharge oil of the first hydraulic pump to a shut-off position that prevents the discharge oil of the first hydraulic pump from being guided to the second hydraulic actuator side, and the second hydraulic pump. Communicating position where both the discharge oil and the pressure oil from the second control valve are guided to the second hydraulic actuator, and the second hydraulic pump and the second hydraulic pump.
A control valve that can switch to a shut-off position that shuts off the second control valve and the second hydraulic actuator, and the first to third control valves according to the operation of the first and second operation members. Switching control means for controlling switching, driving the first hydraulic actuator in a first direction by a first operation of the first operating member, and performing a second operation of the first operating member by the second operation. In the hydraulic circuit of the working vehicle, wherein the first hydraulic actuator is driven in the second direction, and the second hydraulic actuator is driven according to the operation of the second operating member, the switching control means includes: When the first and second operation members are simultaneously operated, the first to third control valves are operated regardless of whether the operation of the first operation member is the first operation or the second operation. Both are characterized by switching to the communication position. The hydraulic circuit of the vehicle. 3. The switching control means includes first switching means for switching the first control valve to the communication position by pressure generated by the first and second operations of the first operating member, The hydraulic pressure for a work vehicle according to claim 2, further comprising: a second switching unit that switches the second control valve to the communication position by a pressure generated by operating the second operating member. circuit. 4. A flow rate adjusting means for adjusting the flow rate of the discharge oil of the first hydraulic pump so that the flow rate introduced into the first control valve is larger than the flow rate introduced into the second control valve. The hydraulic circuit for a work vehicle according to claim 2, wherein the hydraulic circuit is provided. 5. The hydraulic circuit for a work vehicle according to claim 1, wherein the first and second hydraulic actuators drive the first and second work attachments, respectively. . 6. The fifth hydraulic actuator according to claim 5, wherein the first hydraulic actuator is a hydraulic cylinder for raising and lowering an arm, and the second actuator is a hydraulic cylinder for driving a spare attachment. The hydraulic circuit of the work vehicle described.